Adds ruby and unicorn instrumentation

This adds ruby and unicorn instrumentation. This was originally
intended in 11.11 but due to performance concerns it was reverted. This
new commit foregoes the sys-proctable gem was causing performance issues
previously.

1 files changed, 23 insertions, 9 deletions

diff --git a/lib/gitlab/metrics/samplers/unicorn_sampler.rb b/lib/gitlab/metrics/samplers/unicorn_sampler.rb
index bec64e864b3..1b7a4c79080 100644
--- a/lib/gitlab/metrics/samplers/unicorn_sampler.rb
+++ b/lib/gitlab/metrics/samplers/unicorn_sampler.rb
@@ -8,12 +8,16 @@ module Gitlab
           super(interval)
         end
 
-        def unicorn_active_connections
-          @unicorn_active_connections ||= ::Gitlab::Metrics.gauge(:unicorn_active_connections, 'Unicorn active connections', {}, :max)
+        def metrics
+          @metrics ||= init_metrics
         end
 
-        def unicorn_queued_connections
-          @unicorn_queued_connections ||= ::Gitlab::Metrics.gauge(:unicorn_queued_connections, 'Unicorn queued connections', {}, :max)
+        def init_metrics
+          {
+            unicorn_active_connections: ::Gitlab::Metrics.gauge(:unicorn_active_connections, 'Unicorn active connections', {}, :max),
+            unicorn_queued_connections: ::Gitlab::Metrics.gauge(:unicorn_queued_connections, 'Unicorn queued connections', {}, :max),
+            unicorn_workers:            ::Gitlab::Metrics.gauge(:unicorn_workers, 'Unicorn workers')
+          }
         end
 
         def enabled?
@@ -23,14 +27,13 @@ module Gitlab
 
         def sample
           Raindrops::Linux.tcp_listener_stats(tcp_listeners).each do |addr, stats|
-            unicorn_active_connections.set({ socket_type: 'tcp', socket_address: addr }, stats.active)
-            unicorn_queued_connections.set({ socket_type: 'tcp', socket_address: addr }, stats.queued)
+            set_unicorn_connection_metrics('tcp', addr, stats)
           end
-
           Raindrops::Linux.unix_listener_stats(unix_listeners).each do |addr, stats|
-            unicorn_active_connections.set({ socket_type: 'unix', socket_address: addr }, stats.active)
-            unicorn_queued_connections.set({ socket_type: 'unix', socket_address: addr }, stats.queued)
+            set_unicorn_connection_metrics('unix', addr, stats)
           end
+
+          metrics[:unicorn_workers].set({}, unicorn_workers_count)
         end
 
         private
@@ -39,6 +42,13 @@ module Gitlab
           @tcp_listeners ||= Unicorn.listener_names.grep(%r{\A[^/]+:\d+\z})
         end
 
+        def set_unicorn_connection_metrics(type, addr, stats)
+          labels = { socket_type: type, socket_address: addr }
+
+          metrics[:unicorn_active_connections].set(labels, stats.active)
+          metrics[:unicorn_queued_connections].set(labels, stats.queued)
+        end
+
         def unix_listeners
           @unix_listeners ||= Unicorn.listener_names - tcp_listeners
         end
@@ -46,6 +56,10 @@ module Gitlab
         def unicorn_with_listeners?
           defined?(Unicorn) && Unicorn.listener_names.any?
         end
+
+        def unicorn_workers_count
+          `pgrep -f '[u]nicorn_rails worker.+ #{Rails.root.to_s}'`.split.count
+        end
       end
     end
   end